1. Field of the Invention
The present invention relates to apparatus and method for storing and transferring propellant tanks in space.
2. Description of the Related Art
The transportation of cargo between locations in space and maintaining a support platform in orbit is expensive. Part of that cost is propellant, and human development beyond earth orbit currently depends on chemical propellant for transportation to the moon, mars and beyond. High costs create a barrier to the commercial transportation hardware development of space and the investment of private capital in technically viable space transportation ventures. Part of this cost is the expense caused by transferring propellant between vehicles.
Rocket propelled space vehicles travel outside the proximity of the Earth in airless space. Such vehicles may, for example, start a trip from Earth orbit and travel to the surface of the Moon. Such trips use large amounts of propellants, requiring the use of enormous multi-stage rockets to transport the propellant required for the round trip. Such rockets may be similar to the Saturn first stage of the Apollo project, which landed the first man on the Moon more than 30 years ago.
The transfer of cryogenic propellant in the vacuum of space is complicated, difficult to automate, requires precooling, other care and may result in the loss of propellant. Propellant transfer in space is conventionally performed by coupling a single large propellant supply tank with a receiving tank of a vehicle, precooling the receiving tank, transferring the propellant to the receiving tank, and decoupling the tanks. Such systems require precision coupling, propellant settling, precooling, boil-off and leak prevention, sensing of quantities and flow rates, and sophisticated designs for tanks and sensors, which result in very complex transfer processes on earth in one gravity. The lack of gravity adds another level of complexity and is difficult to fully automate.